**Core Concept**
The patient's presentation of hematuria, family history of a 'blood disease', and abnormal hemoglobin electrophoresis suggests a possible diagnosis of sickle cell disease, a genetic disorder characterized by the production of abnormal hemoglobin (Hb S). This abnormal hemoglobin causes red blood cells to become misshapen and prone to premature destruction, leading to various clinical manifestations including hematuria.

**Why the Correct Answer is Right**
The patient's hemoglobin electrophoresis shows a significant presence of Hb S (40%), indicating a diagnosis of sickle cell trait (Hb AS). In sickle cell trait, the individual has one normal hemoglobin gene (Hb A) and one sickle hemoglobin gene (Hb S). This condition is usually asymptomatic but can increase the risk of complications in certain situations, such as high altitudes or infections. The hematuria in this patient may be due to sickling of red blood cells in the renal medulla, leading to microvascular occlusion and subsequent hemolysis.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not take into account the patient's family history of a 'blood disease' and the abnormal hemoglobin electrophoresis results. While it is a possible cause of hematuria, it is not the most likely diagnosis in this case.
**Option B:** This option is incorrect because it does not explain the patient's hemoglobin electrophoresis results. The patient's hemoglobin levels are within normal limits, making this option less likely.
**Option C:** This option is incorrect because it does not consider the patient's family history and the presence of Hb S on hemoglobin electrophoresis. While it is a possible cause of hematuria, it is not the most likely diagnosis in this case.

**Clinical Pearl / High-Yield Fact**
Sickle cell trait (Hb AS) is a milder form of sickle cell disease and is often asymptomatic. However, it can increase the risk of complications in certain situations, such as high altitudes or infections. It is essential to consider sickle cell trait in patients with a family history of a 'blood disease' and abnormal hemoglobin electrophoresis results.

**Correct Answer:** C.